It's a simple idea, but a radical one. Let people know in advance how much health care will cost them—and whether they can find a better deal somewhere else.

With outrage growing over incomprehensible medical bills and patients facing a higher share of the costs, momentum is building for efforts to do just that. Price transparency, as it is known, is common in most industries but rare in health care, where "charges," "prices," "rates" and "payments" all have different meanings and bear little relation to actual costs.

Unlike other industries, prices for health care can vary dramatically depending on who's paying. The list prices for hospital stays and doctor visits are often just opening bids that insurers negotiate down. The deals insurers and providers strike are often proprietary, making comparisons difficult. Even doctors are generally clueless about what the tests, drugs and specialists they recommend will cost patients.